1 # 2 # (Generic) Netlink message generation/parsing 3 # Copyright (c) 2007 Johannes Berg <johannes@sipsolutions.net> 4 # Copyright (c) 2014 Intel Corporation 5 # 6 # This software may be distributed under the terms of the BSD license. 7 # See README for more details. 8 9 import struct, socket 10 11 # flags 12 NLM_F_REQUEST = 1 13 NLM_F_MULTI = 2 14 NLM_F_ACK = 4 15 NLM_F_ECHO = 8 16 17 # types 18 NLMSG_NOOP = 1 19 NLMSG_ERROR = 2 20 NLMSG_DONE = 3 21 NLMSG_OVERRUN = 4 22 NLMSG_MIN_TYPE = 0x10 23 24 class Attr(object): 25 def __init__(self, attr_type, data, *values): 26 self._type = attr_type 27 if len(values): 28 self._data = struct.pack(data, *values) 29 else: 30 self._data = data 31 32 def _dump(self): 33 hdr = struct.pack("HH", len(self._data) + 4, self._type) 34 length = len(self._data) 35 pad = ((length + 4 - 1) & ~3) - length 36 return hdr + self._data + b'\x00' * pad 37 38 def __repr__(self): 39 return '<Attr type %d, data "%s">' % (self._type, repr(self._data)) 40 41 def u16(self): 42 return struct.unpack('H', self._data)[0] 43 def s16(self): 44 return struct.unpack('h', self._data)[0] 45 def u32(self): 46 return struct.unpack('I', self._data)[0] 47 def s32(self): 48 return struct.unpack('i', self._data)[0] 49 def str(self): 50 return self._data 51 def nulstr(self): 52 return self._data.split('\0')[0] 53 def nested(self): 54 return parse_attributes(self._data) 55 56 class StrAttr(Attr): 57 def __init__(self, attr_type, data): 58 Attr.__init__(self, attr_type, "%ds" % len(data), data) 59 60 class NulStrAttr(Attr): 61 def __init__(self, attr_type, data): 62 Attr.__init__(self, attr_type, "%dsB" % len(data), data, 0) 63 64 class U32Attr(Attr): 65 def __init__(self, attr_type, val): 66 Attr.__init__(self, attr_type, "I", val) 67 68 class U8Attr(Attr): 69 def __init__(self, attr_type, val): 70 Attr.__init__(self, attr_type, "B", val) 71 72 class FlagAttr(Attr): 73 def __init__(self, attr_type): 74 Attr.__init__(self, attr_type, b"") 75 76 class Nested(Attr): 77 def __init__(self, attr_type, attrs): 78 self.attrs = attrs 79 self.type = attr_type 80 81 def _dump(self): 82 contents = [] 83 for attr in self.attrs: 84 contents.append(attr._dump()) 85 contents = ''.join(contents) 86 length = len(contents) 87 hdr = struct.pack("HH", length+4, self.type) 88 return hdr + contents 89 90 NETLINK_ROUTE = 0 91 NETLINK_UNUSED = 1 92 NETLINK_USERSOCK = 2 93 NETLINK_FIREWALL = 3 94 NETLINK_INET_DIAG = 4 95 NETLINK_NFLOG = 5 96 NETLINK_XFRM = 6 97 NETLINK_SELINUX = 7 98 NETLINK_ISCSI = 8 99 NETLINK_AUDIT = 9 100 NETLINK_FIB_LOOKUP = 10 101 NETLINK_CONNECTOR = 11 102 NETLINK_NETFILTER = 12 103 NETLINK_IP6_FW = 13 104 NETLINK_DNRTMSG = 14 105 NETLINK_KOBJECT_UEVENT = 15 106 NETLINK_GENERIC = 16 107 108 class Message(object): 109 def __init__(self, msg_type, flags=0, seq=-1, payload=None): 110 self.type = msg_type 111 self.flags = flags 112 self.seq = seq 113 self.pid = -1 114 payload = payload or [] 115 if isinstance(payload, list): 116 self.payload = bytes() 117 for attr in payload: 118 self.payload += attr._dump() 119 else: 120 self.payload = payload 121 122 def send(self, conn): 123 if self.seq == -1: 124 self.seq = conn.seq() 125 126 self.pid = conn.pid 127 length = len(self.payload) 128 129 hdr = struct.pack("IHHII", length + 4*4, self.type, 130 self.flags, self.seq, self.pid) 131 conn.send(hdr + self.payload) 132 133 def __repr__(self): 134 return '<netlink.Message type=%d, pid=%d, seq=%d, flags=0x%x "%s">' % ( 135 self.type, self.pid, self.seq, self.flags, repr(self.payload)) 136 137 @property 138 def ret(self): 139 assert self.type == NLMSG_ERROR 140 return struct.unpack("i", self.payload[:4])[0] 141 142 def send_and_recv(self, conn): 143 self.send(conn) 144 while True: 145 m = conn.recv() 146 if m.seq == self.seq: 147 return m 148 149 class Connection(object): 150 def __init__(self, nltype, groups=0, unexpected_msg_handler=None): 151 self.descriptor = socket.socket(socket.AF_NETLINK, 152 socket.SOCK_RAW, nltype) 153 self.descriptor.setsockopt(socket.SOL_SOCKET, socket.SO_SNDBUF, 65536) 154 self.descriptor.setsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF, 65536) 155 self.descriptor.bind((0, groups)) 156 self.pid, self.groups = self.descriptor.getsockname() 157 self._seq = 0 158 self.unexpected = unexpected_msg_handler 159 def send(self, msg): 160 self.descriptor.send(msg) 161 def recv(self): 162 contents = self.descriptor.recv(16384) 163 # XXX: python doesn't give us message flags, check 164 # len(contents) vs. msglen for TRUNC 165 msglen, msg_type, flags, seq, pid = struct.unpack("IHHII", 166 contents[:16]) 167 msg = Message(msg_type, flags, seq, contents[16:]) 168 msg.pid = pid 169 if msg.type == NLMSG_ERROR: 170 import os 171 errno = msg.ret 172 if errno < 0: 173 err = OSError("Netlink error: %s (%d)" % ( 174 os.strerror(-errno), -errno)) 175 err.errno = -errno 176 raise err 177 return msg 178 def seq(self): 179 self._seq += 1 180 return self._seq 181 182 def parse_attributes(data): 183 attrs = {} 184 while len(data): 185 attr_len, attr_type = struct.unpack("HH", data[:4]) 186 attrs[attr_type] = Attr(attr_type, data[4:attr_len]) 187 attr_len = ((attr_len + 4 - 1) & ~3) 188 data = data[attr_len:] 189 return attrs 190 191 192 193 CTRL_CMD_UNSPEC = 0 194 CTRL_CMD_NEWFAMILY = 1 195 CTRL_CMD_DELFAMILY = 2 196 CTRL_CMD_GETFAMILY = 3 197 CTRL_CMD_NEWOPS = 4 198 CTRL_CMD_DELOPS = 5 199 CTRL_CMD_GETOPS = 6 200 201 CTRL_ATTR_UNSPEC = 0 202 CTRL_ATTR_FAMILY_ID = 1 203 CTRL_ATTR_FAMILY_NAME = 2 204 CTRL_ATTR_VERSION = 3 205 CTRL_ATTR_HDRSIZE = 4 206 CTRL_ATTR_MAXATTR = 5 207 CTRL_ATTR_OPS = 6 208 209 class GenlHdr(object): 210 def __init__(self, cmd, version=0): 211 self.cmd = cmd 212 self.version = version 213 def _dump(self): 214 return struct.pack("BBxx", self.cmd, self.version) 215 216 def _genl_hdr_parse(data): 217 return GenlHdr(*struct.unpack("BBxx", data)) 218 219 GENL_ID_CTRL = NLMSG_MIN_TYPE 220 221 class GenlMessage(Message): 222 def __init__(self, family, cmd, attrs=[], flags=0): 223 Message.__init__(self, family, flags=flags, payload=[GenlHdr(cmd)] + attrs) 224 225 class GenlController(object): 226 def __init__(self, conn): 227 self.conn = conn 228 def get_family_id(self, family): 229 a = NulStrAttr(CTRL_ATTR_FAMILY_NAME, family) 230 m = GenlMessage(GENL_ID_CTRL, CTRL_CMD_GETFAMILY, flags=NLM_F_REQUEST, attrs=[a]) 231 m.send(self.conn) 232 m = self.conn.recv() 233 gh = _genl_hdr_parse(m.payload[:4]) 234 attrs = parse_attributes(m.payload[4:]) 235 return attrs[CTRL_ATTR_FAMILY_ID].u16() 236 237 genl_controller = GenlController(Connection(NETLINK_GENERIC)) 238